1. Field of the Invention
An object of the present invention is an antenna structure with symmetrical strip line type microwave energy distribution circuits.
2. Description of the Prior Art
One prior art antenna uses a plurality of radiating elements distributed, in a plane, in N rows and M columns. The scanning of space by the microwave beam thus obtained is done by mechanical rotation on one or two axes or, again, by electronic scanning in one or two planes, with electronically controllable phase shifters being then added to the structure.
When this type of antenna uses only one microwave energy source, this energy has to be divided, for example first of all vertically, among N horizontal planes and then distributed horizontally among the M radiating elements borne by each horizontal plane.
Since an energy distribution such as this has to be done with a minimum loss, symmetrical strip line type circuits are generally used, notably, suspended symmetrical strip line circuits, namely symmetrical strip line circuits wherein the dielectric is formed by air.
Thus a stack of N symmetrical strip line circuits is obtained, each distributing the energy to M radiating elements and being separated from one another by spacers to maintain the pitch, in the vertical direction, chosen for the radiating elements.
An arrangement such as this generally forms a heavy and bulky antenna. Furthermore, the making of the symmetrical strip line distribution circuits becomes difficult when their size increases, thus restricting the number M of radiating elements per distributor.